* The rw_lock is now able to nest read/write locks when you have a write lock.

It follows the semantics of the BFS R/W lock, though, that is, if you unlock
  your write lock before the read locks, the read locks effectively become
  write locks, too.
* Added a mutex_transfer_lock() function that will allow you to unlock a mutex
  in a different thread than the one which locked it (only matters if KDEBUG
  is enabled, though).


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@26316 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/lock.h

@@ -46,6 +46,7 @@ typedef struct rw_lock {
 	thread_id				holder;
 	int32					reader_count;
 	int32					writer_count;
+	int32					owner_count;
 	uint32					flags;
 } rw_lock;
 
@@ -159,6 +160,15 @@ mutex_unlock(mutex* lock)
 }
 
 
+static inline void
+mutex_transfer_lock(mutex* lock, thread_id thread)
+{
+#ifdef KDEBUG
+	lock->holder = thread;
+#endif
+}
+
+
 extern void lock_debug_init();
 
 #ifdef __cplusplus